S1
(also s)
¦ noun (plural Ss or S's)
1. the nineteenth letter of the alphabet.
2. denoting the next after R in a set of items, categories, etc.
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S2
¦ abbreviation
1. (chiefly in Catholic use) Saint.
2. siemens.
3. small (as a clothes size).
4. South or Southern.
5. Sweden (international vehicle registration).
¦ symbol
1. the chemical element sulphur.
2. Chemistry entropy.